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ALBERT C. WILLSON, OF GREEN POINT, NEW YORK.

Letters Patent No. 76,867, dated April 14, 1868.

IMPROVED FERRY-BRIDGE.

fltlge firlgnnlc reform In in these Zhtters patent mnmating part of tip same.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, ALBERT G. WILLSON, of Green Point, county of Kings, and State of New York, have invented a new and improved Mode of Elevating and Depressing Ferry and other Floating Bridges; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being bad to the accompanying drawing, and to the letters of reference marked thereon. I

The nature of my invention consists in providing a variable float, so constructed and placed, in relation to the bridge, that by its oscillation or vibration it elevates or depresses the bridge at the will of the operator.

i To enable others skilled in the art to make and use my invention, I will proceed, first, to explain the uses and requirements of such an invention, and second, to describe the construct-ion and operation of the invention itself. v

A ferry-boat, plying between two points, flouting upon the surface of the water, is subject to tidal variations, and it becomes necessary, at the points of landing, to intervene between the boat and the dock a bridge, to facilitate the landing of passengers and teams. This bridge, by its being hinged to the dock, in such a manner that its opposite end may be elevated or depressed to suit the various heights of the boat, forms a convenient passage for passengers and teams from the boat to the dock at all times of tide.

he original method of supporting the movable end of the bridge was by connecting it by chains to the ends of two levers, placed at a considerable distance above the bridge, and supported in their position upon a substantial framework built upon the dock. At the opposite ends of these levers were placed sufiicient weights to nearly counterbalance the weight of the movable end of the bridge, which was elevated or depressed by means of supplementary chains attached to the framework, resting upon the dock, and to windlasses fixed upon the bridge. This plan, although very eli'ective, required considerable labor illmanipulation, and in point of construction was exceedingly dangerous to human life, as the supplementary chains having to support not only part of the weight of the bridge, but also the weight of passengers and teams passing to and fro, or waiting upon it for the boat to arrive, were exceedingly liable to break, especially in cold weather, thereby prccipitat ing the bridge and everything upon it into the water below.

After the distressing accident which occurred some years ago at the Staten Island ferry,New York city, caused by the breaking of the supplementarychains, by which many lives were lost, an ordinance was passed prohibiting the further construction of this means of supporting the movable end of the bridge, and requiring the substitution of floats for that purpose. This float, as at present constructed, floats upon the surface of the 7 water, underneath the bridge, and is to the bridge what the lovers and weights were in the original plan. This float, resting upon the surface of the water, regulates the bridge to all tidal variations, but does not regulate it to the various heights of the boats. i

The plan usually adopted to overcome this difliculty in floating-bridges is precisely the same as in the original plan, namely: A supplementary chain, attached to a. framework, resting upon the dock, and to a windlass fixed upon the bridge, so that the float and bridge may, by operating the Windlass, be drawn up out of the water, so to speak, or depressed by allowing them to sink down by their own gravity. Now, it sometimes occurs that two boats, running upon the same ferry, have altogether a different draught of water. This difference is in many instances several feet, and if the buoyancy of the float is such as to elevate the bridge to the height of the higher boat, it will not sink low enough to reach the level of the lower one, and in order that teams may drive 011' and on the boat, a gang-plank has to be used. This gang-plank forms a steep inclined plane between the boat and the bridge, and is exceedingly detrimental to the passage of heavy loads'from the boat to the dock. On the other hand, if the float be filled with water to such an extent as 'to cause it to sink low enough to accommodate the bridge to the level of the lower boat, it has to be raised alternately to the height of the higher one by the means of the supplementary chain. This, together with the weight of the teams, or.whatever I may be upon the bridge at the time, brings such a great strain upon'the chain that it often breaks, especially in cold weather, and although suchaccidents are not always attended with,as serious results as-in the case cited of the original plan, still, loss of life is likely to occur, and expense for repairs is involved, as Well as delay.

Having had many years experience in these matters, it was the'dbsire to remedy these evils that led to my invention, which I will now proceed to describe.

The bridge proper, A, I construct in the usual manner, that is to say, the end of the bridge at a has fast upon it the string-piece b, which rests in a groove formed in the timbers of the dock B. This forms a hinge,

which allows the opposite end of the bridge to vibrate up and down withoutthe bridge becoming detached from the dock. The end of the bridge at c is curved in shape to conform to the bows of the boat, and is supported in its position by the float C. This float C is rectangular in shape, and rests or floats upon the surface of the water, underneath the bridge. Between the end, 0, of the bridge and the float, another hinge is constructed in a like manner as the one between the dock and bridge, at a, which allows a free vibration of thefioat O, without its becoming detached from the bridge A. This hinge I place as close as convenient to the side, 17, of the float, in order to have it as far as possible from the centre of buoyancy of the float, which is at a when the float is in the position shown on the drawing. At the opposite side,f, of the float I fasten two levers, D I), and at their extremities, ,qg, I connect them by the cross-bar E, and also by the platform F. At the centre of the cross-bar E, I fasten a rope or chain, it h It, which passes over the two pulleys i 2', which are placed in the framing of the bridge, and from thence to the windlass G, which is fixed upon the bridge in such a position as to be conveniently operated, and at the same time not obstruct the travel upon the bridge. Upon the platform F, I place suflicient weights, jjj, such as will give it a preponderanceiover that of the end of the bridge, and the weight thatmay ever come upon it. v

The operation of the bridge is as follows: As is the case with all floating-bridges, the float resting upon the surface of the water, regulates the bridge to all tidal variations, but it often occurs that the boat arr-ides at the, bridge more heavily laden than at other times, and her bows are consequently lower down, so much so as, in some instances, to pass completely under the bridge. In such a case, by operating the windlass, I raise the weights and platform, which, by their connection tilt or vibrate the float. Now it is well known that any vessel or body resting upon the surface of the water may be tilted or vibrated at will, and the vibrations are always upon a given centre, which is called the centre of buoyancy. As the float vibrates upon its centre of buoyancy, which is the centre of gravity of the water displaced by the float, it the side,f, be raised with the levers DD and weights jjj, the opposite side, d, sinks lower in the water, carrying with it the end of the bridge, which operation may be carried on until the bridge becomes level with the boat. In raising the bridge, the operation is simply the reverse, both operations being shown by the redlines Ia lc'lc,&c.

The principal advantage I claim for this invention is its entire freedom from all the disadvantages heretofore enumerated as existing in all other floating-bridges. As the bridge is very readily elevated or depressed, the gang-plank is dispensed with, as the bridge may at anytime be brought to an exact level with the boat.

Accidents caused by an undue strain upon the chain can never occur, as it will readily be seen that an unusual weight upon the bridge tends to relieve the strainupon the chain, and can never increase it, and even should the chain break from any extraordinary cause, the bridge would simply be elevated, and not precipitated to the water. The means forelevating and depressing are entirely within the bridge, having no connection whatever with the dock for that purpose. I

' The construction of my float, as herein described, may be varied. Where I have not suflieient: room between the dock and the movable end of the bridge to admit of the levers, I construct a. bulk-head inside the float, as near as possible to the side opposite that upon which the bridge rests, leaving a space of sufiicient cubical capacity to receive suflieient weights between said bulk-head and the side of thefloat such as will give that side a preponderdnce over that of the other, with the weight of the bridge resting upon it. I then attach my chain directly to the side of the float, and from thence over the pulleys a i to the Windlass. The operation of this variation is substantially the sameas my original invention, for while I acknowledge the priority of the use of the float to regulate the bridge to tidal variations,

I do claim, and desire to secure by Letters Patent- I t For elevating or depressing the bridge at will, the-variable float C, constructed and operated substantially as herein described.

Witnesses:

Gam. Kmrr, Geo. W. Qumrann.

ALBERT C. WILLSON. 

